In the 50-50 U.S. Senate, Democrats only have the majority thanks to Vice President Kamala Harris serving as a tie-breaking vote. That could change after the upcoming November midterm elections, now 98 days away. There are many open and competitive seats, to be sure. Republicans may retake control of the Senate, just as they are predicted to do with the U.S. House of Representatives. The Senate, however, is considered more of a toss-up, so it's also possible that the Democrats may expand their majority, though at least with a Republican-controlled House they wouldn't control both chambers plus the White House.
On Tuesday night, Missouri Republicans handily nominated state Attorney General Eric Schmitt to run to replace retiring Sen. Roy Blunt (R-MO). The race is considered to heavily favor Republicans. Cook Political Report and Inside Elections regard the race as "Solid Republican" while Sabato's Crystal Ball says it's "Likely Republican."
Later on Tuesday night, though, results are expected to come in with the Arizona Republican primary, where the nominee will face Sen. Mark Kelly (D-AZ). The vulnerable incumbent was elected in 2020 in a special election against then Sen. Martha McSally (R-AZ), who had been appointed by Doug Ducey, the state's Republican governor, to replace interim Sen. John Kyl (R-AZ), who had been appointed to replace the late Sen. John McCain (R-AZ).
This race, on the other hand, is considered a "Toss-Up," by all three of the outlets mentioned above.
Decision Desk HQ, on Monday night, gave Kelly a 75.9 percent chance to win re-election, though it's worth noting they acknowledged Tuesday's "long-awaited Republican primary could move that number in either direction." Further, they also tend to give incumbents a significant advantage.
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On 'Election Eve' in Arizona, DDHQ gives incumbent Sen. Mark Kelly (D) a 75.9% chance of winning re-election this November, but tomorrow's long-awaited Republican primary could move that number in either direction: https://t.co/UEv7lvrSoC pic.twitter.com/wVKTVApZ0J
— Decision Desk HQ (@DecisionDeskHQ) August 1, 2022
In a video about Tuesday's primaries posted to the Decision Desk HQ YouTube account last Friday, Brandon Finnigan tellingly noted though, that while Kelly was the favorite to win in 2020, he ultimately won by a slimmer margin than he was leading in the polls. Finnigan went on to explain "we have seen a pattern of the Republican vote having been, ehh, missed shall we say, when it comes to polling in U.S. Senate races," with examples coming in 2020 with Sen. Susan Collins (R-ME) and even in 2014, with now Sen. Tom Cotton (R-AR), and in 2010, with now Sen. Marco Rubio (R-FL).
Blake Masters is considered the frontrunner among a crowded field of five candidates plus two write-in candidates vying to face Sen. Kelly come November. Masters, who turns 36 later this week, has served as the chief operating officer of Thiel Capital and the president of the Thiel Foundation, with significant backing from Peter Thiel. He was also endorsed by former President Donald Trump in June and appeared with the former president at a rally in Prescott Valley last month.
Masters has certainly embraced his endorsement from Trump, promising an "America First" campaign.
Endorsed by President Trump! Doesn’t get any better. Sights set on November 8. The message: America First. ????
— Blake Masters (@bgmasters) June 2, 2022
Sen. Kelly is fourth on a list from RollCall of 10 most vulnerable senators back in May. A CNN projection from last month rates the Arizona Senate seat as a "Toss-Up," including Kelly as a vulnerable incumbent. He's fourth there too on that outlet's list of 10 most vulnerable senators. A POLITICO analysis from May about which seven states will decide control of the Senate, includes Kelly's race, also considering it to be a "Toss-Up." The Democratic senator is likewise included in a June list from The Hill of seven Senate seats most likely to flip this year.
In a lengthy analysis from The New York Times about the midterms, last updated on May 3, "Republican challengers to Mark Kelly in Arizona" are part of a piece about 10 Senate races to watch.
An interactive from USA Today about top Senate races to watch also notes that Kelly "may face an uphill battle in defending his seat."
Another particularly vulnerable incumbent is also a Democrat, Sen. Catherine Cortez Masto (D-NV), who faces Adam Laxalt in November, the state's former attorney general.
She was first on that list of vulnerable senators from RollCall in May, and included in coverage from the Associated Press, The Washington Times, and POLITICO, that emphasized her as a "vulnerable" incumbent.
That U.S. Senate race in Nevada is also considered a "Toss-Up."